OK sudden symptom's truck was running fine getting off freeway and motor start's to come to a Idle and it start's shaking and oil light flicker's rev it up it sound's fine but won't Idle now What the heck do I check and Look for ?

 

Did the lock nut on the low idle screw back off?

What is your fuel pressure reading ?

Lift pump, factory pressure, would be in the 3-5PSI rating out of the fuel filter. If it's less than that, then either your filter is clogged, or the lift pump isn't performing what it should.

No other symptoms ? Smoke ?

radio and lights go out? If so, then look in the sky for a UFO, as I hear that's what happens when they're about to abduct you and probe your buttox with a big metal thingy.....

 

The lock nut on idle screw is what I am thinking and will check it tomorrow . there was No Smoke or anything Egt's were less then 1000 that is Only gauge I have hooked up right now Have boost and trans temp just waiting to be hooked up . But needed truck today so I could change front yoke , transfer case rear seal and rear yoke seal I was tired of Leak's then on way home it idled funny .So hope it's either idle screw or fuel screw . We Will See .Thank's for the Help

 

Ok everything look's tight but idle was way off turned it up and it run's fine . I'm going to throw a fuel filter on it just because it's time and see how it does . What else could it be ? haven't found anything Loose yet .but still looking for Idea's

 

How are the teeth on the throttle arm to throttle shaft? Set screws look good in the throttle arms? What is your idle fuel psi from lift pump?

 

Have to check the arm to make sure it's tight didn't think about that side of it . I do not know pressure but will figure out how to check it idel screw was tight so was fuel screw . I turned the idle screw in more and it run's fine again .I'm going to put a fuel filter on it tomorrow just because it's time but what was funny was off Idle it ran fine . but will check the throttle arm tomorrow and go from there .

 

OK arm is tight adjusted the idle up some and took it for a drive and when I pulled over to stop it jumped up to 1100 rpm's and stayed there so I took it back home and readjusted the Idle now it's idleing but also sound's like it's surging ? HELPPPPPPPPPPPPPP This is what is stumping me it run's fine going down the road shift's great throu the gear's and now idles but it is surging what else can I check . If it was fuel pressure you would think it would bog down at higher RPM ? No ??

 

Check the lift pump, with the engine down (off) try to prime it. The lever should get rock hard or present with some resistance. Also, take the top half of the pump off four screws (assuming this is a VE?) and check for diesel fuel in there or any sign of wetness.

Also, can you make sure the index bolt is snug and on target?

 

Checked top of Pump everything is Tight going to check lift pump and go from there . That is what I am thinking it is . The VE will suck enough fuel to keep it running but without the lift pump it will run funny and I believe that is where I am at right now .Dieing Lift pump
Thank's guy's for the info .

 

A bad lift pump won't put out much fuel at idle. I almost think you have something hanging up internally in the VE though

 

What could be hanging up thou ? truck has been running Flawless up untill Sunday . Can't Blame it on the Bronco's thou Manning didn't touch it . LOL . Maybe a Broken gov spring ? I'm at a Loss to be honest .

 

I don't think it would be the governor spring, could be wrong though. Supply line sucking air? Leak around the pump banjo bolt?

 

Well I am below a 1/4 and just shy of fuel light on but it shouldn't be sucking fuel .????

 

for the heck of it add 10 gallons of fuel to see if anything changes, a bad pump wont allow any load, easy way to check it, when running, open bleeder, and check volume, and aeration, if you get a good steady flow, your good, most of the time I see diaphrams go bad, and they leak externally, if its internal, the oil level will climb, if its air coming from the pickup,, it can run with his symptoms, hence, aeration, if theres no change adding fuel, id pop off the ve pump cover to investigate a part failure, something could have broken, causing interference with the governor, your worst fear is a runaway, be prepared for a quick shutdown, ive read enough of these threads to know yours is out of any normal failure, be careful.

 

I was talking about sucking air along the fuel line after the tank before the LP. How did you lengthen the lines? Maybe wore against something? They don't always leak fuel but can suck air